This invention relates to a novel oil filter apparatus. More particularly the invention comprises a combination of an electronic apparatus for monitoring and signaling the condition of an oil filter operable to remove solid contaminates and water or other volatile contaminates from engine lubricating oils.
Internal combustion engines, and the like, having a large number of relative moving parts are continuously lubricated by an associated lubrication system. The lubrication system typically includes an oil sump from which oil is pumped in a fluidic loop or splashed around and over moving engine parts such as valves, piston rods, etc. In order to eliminate abrasives which become suspended within the lubrication system the oil is continuously pumped through an oil filter mounted in series with the oil loop. In addition to abrasives however, water and other entrained liquid contmainates should be removed to prevent "sludge" buildup. If both solid and liquid contaminates can be reliably removed it becomes unnecessary to change the oil since the oil per se does not "wear out" but rather becomes contaminated with solid and liquid impurities.
It is critical to maintain lubricating oils clean when lubricating expensive machinery such as internal combustion machines. The prior art teaches many variations in replaceable filters for such purposes. It is difficult for the operator of machinery, however, to determine when a filter must be replaced. Therefore, manufacturers of such equipment typically recommend that filters should be replaced after "so many hours of operation" or "after so many miles traveled". These methods are imprecise and often lead to the retention of filters past their useful life with subsequent damages to an engine or the filters are replaced unnecessarily before replacement is required. As more expensive and sophisticated filtering equipment is utilized an incentive exists to extend the useful life of the filter while concomitantly accurately determining when a filter needs replacement.
One method for increasing the useful life of filters is to insure that the oil to be cleaned is heated to a sufficient degree to evaporate entrained liquid impurities such as water. In this connection water combines with other impurities to form sludge which leads to an early clogging of a filter media. Although such heating apparatus is relatively expensive it does not provide an operator with a means for determining the effectiveness of the heating means in extending the life of the filter. One example of a heating device used in association with an oil filter is shown in an Engel U.S. Pat. No. 4,189,351, issued Feb. 19, 1980.
Other workers in the field have developed means for sensing the degree of resistance filtered oil encounters via its travel through a filter by sensing the difference in oil pressure between an inlet and outlet and, upon sensing a predetermined difference, activating an alarm for signalling the operator that the filter is clogged.
At least one previously known system is designed to signal actuation of an engine mounted bypass valve. In this regard the valve structure is placed in series with an engine battery and in parallel with an alarm. In the event the bypass valve and circuit are opened the battery will conduct through the alarm thus signalling opening of the bypass valve.
While such a system provides at least a degree of theoretical appeal one disadvantage is that alarm systems of this type require special fitting within an oil system. Additionally a potential for sparking exists within the oil system when the bypass electrical circuit is broken. Still further such bypass valves are subject to "chatter" during starting, etc. due to temporary high loads.
One system which advantageously obviates many of the disadvantaes of previously known bypass systems is disclosed and claimed in my copending U.S. application Ser. No. 77,832, filed Sept. 21, 1979 and now U.S. Pat. No. 4,246,109. The disclosure of this patent is hereby incorporated by reference as though set forth at length.
A difficulty with my prior disclosed bypass system is that the bypass structure tends to be relatively expensive when compared with many filter canisters. Moreover the inferior character of most filtering media and systrems dictates relatively rapid replacement.
The difficulties suggested in the preceding are not intended to be exhaustive, but rather are among many which may tend to reduce the effectiveness of prior oil filter methods and apparatus. Other noteworthy problems may also exist; however, those presented above should be sufficient to demonstrate that oil filter methods and apparatus appearing in the past will admit to worthwhile improvement.